mm: swap: swap ratio support
Add support to receive a static ratio from userspace to
divide the swap pages between ZRAM and disk based swap
devices. The existing infrastructure allows to keep
same priority for multiple swap devices, which results
in round robin distribution of pages. With this patch,
the ratio can be defined.
Change-Id: I54f54489db84cabb206569dd62d61a8a7a898991
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 0435487..9cf2595 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -81,8 +81,8 @@
* is held and the locking order requires swap_lock to be taken
* before any swap_info_struct->lock.
*/
-static PLIST_HEAD(swap_avail_head);
-static DEFINE_SPINLOCK(swap_avail_lock);
+PLIST_HEAD(swap_avail_head);
+DEFINE_SPINLOCK(swap_avail_lock);
struct swap_info_struct *swap_info[MAX_SWAPFILES];
@@ -216,7 +216,6 @@
}
}
-#define SWAPFILE_CLUSTER 256
#define LATENCY_LIMIT 256
static inline void cluster_set_flag(struct swap_cluster_info *info,
@@ -671,18 +670,39 @@
{
struct swap_info_struct *si, *next;
pgoff_t offset;
+ int swap_ratio_off = 0;
if (atomic_long_read(&nr_swap_pages) <= 0)
goto noswap;
atomic_long_dec(&nr_swap_pages);
+lock_and_start:
spin_lock(&swap_avail_lock);
start_over:
plist_for_each_entry_safe(si, next, &swap_avail_head, avail_list) {
+
+ if (sysctl_swap_ratio && !swap_ratio_off) {
+ int ret;
+
+ spin_unlock(&swap_avail_lock);
+ ret = swap_ratio(&si);
+ if (ret < 0) {
+ /*
+ * Error. Start again with swap
+ * ratio disabled.
+ */
+ swap_ratio_off = 1;
+ goto lock_and_start;
+ } else {
+ goto start;
+ }
+ }
+
/* requeue si to after same-priority siblings */
plist_requeue(&si->avail_list, &swap_avail_head);
spin_unlock(&swap_avail_lock);
+start:
spin_lock(&si->lock);
if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) {
spin_lock(&swap_avail_lock);
@@ -2566,9 +2586,11 @@
mutex_lock(&swapon_mutex);
prio = -1;
- if (swap_flags & SWAP_FLAG_PREFER)
+ if (swap_flags & SWAP_FLAG_PREFER) {
prio =
(swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
+ setup_swap_ratio(p, prio);
+ }
enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",